A brush with design

A miniature tractor with bristles instead of wheels for traction has transformed the way that pipelines can be inspected and maintained. Based on the concept of a pair of cylindrical gripping brushes connected by a reciprocating cylinder that acts as a rod, the tractor can reach previously inaccessible areas of the pipe networks used by the water, chemical, nuclear and oil industries. By equipping the tractor with a variety of tools, it can be used to inspect and maintain pipes remotely, for example, by putting in temporary seals or valves, or maintaining the flow of oil in deep sea offshore pipelines.

The technology has been developed from research originally undertaken by engineers at the University of Durham. It works on the principal of the bottlebrush, in that it is easier to push a cylindrical brush into a narrower tube than it is to pull it out. Understanding how individual bristles buckle and grip tube walls has helped the company develop and build a series of tractors specialised to solve all kinds of industry problems.

The technology is licensed exclusively to the spin-out company, Durham Pipeline Technology Ltd (DPT), which designs the tractors to be either self-powered or remotely driven via an 'umbilical'. The machines are proving popular with many of the industries that rely on pipe networks. For example, the tractor is being kept busy by the nuclear industry, whose reactors were designed to be as compact as possible, making many of its pipe systems particularly inaccessible.

The technology has won an award for its services to the water industry, where it provides an alternative system for cleaning underground mains that does not require large amounts of pressurised water to propel the cleaning tool through the pipes. It can be adapted to clean and inspect pipes of different dimensions. 'The DPT tractor managed to examine 19 out of 20 sewers that were un-inspectable using traditional machines,' says Ernie Appleton, DPT Technical Director. 'This provides significant cost savings, as contractors can avoid digging holes in inconvenient places, only to discover that just a small part of the pipe is actually damaged.'

More recently, DPT has been looking at ways of using the technology to 'pig' or clean offshore pipelines. It can be introduced to the pipe from the oilrig and travels towards the wellhead against the flow of the oil.